Activity Associated with Derivative Instruments (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Derivative [Line Items]
Notional amount, beginning balance	$ 28,091
Additions	5,119
Maturities/ terminations	(6,514)
Notional amount, end balance	26,696
Derivatives not designated as hedges
Derivative [Line Items]
Notional amount, beginning balance	13,520
Additions	5,002
Maturities/ terminations	(6,120)
Notional amount, end balance	12,402
Derivatives not designated as hedges | Interest rate swaps
Derivative [Line Items]
Notional amount, beginning balance	7,200
Additions	1,359
Maturities/ terminations	(796)
Notional amount, end balance	7,763
Derivatives not designated as hedges | Interest rate swaps | Securitization Entities
Derivative [Line Items]
Notional amount, beginning balance	117
Additions
Maturities/ terminations	(6)
Notional amount, end balance	111
Derivatives not designated as hedges | Credit default swaps
Derivative [Line Items]
Notional amount, beginning balance	1,110
Additions	100
Maturities/ terminations	(130)
Notional amount, end balance	1,080
Derivatives not designated as hedges | Credit Default Swaps Related to Securitization Entities
Derivative [Line Items]
Notional amount, beginning balance	314
Additions
Maturities/ terminations	(2)
Notional amount, end balance	312
Derivatives not designated as hedges | Equity index options
Derivative [Line Items]
Notional amount, beginning balance	522
Additions	503
Maturities/ terminations	(558)
Notional amount, end balance	467
Derivatives not designated as hedges | Financial futures
Derivative [Line Items]
Notional amount, beginning balance	2,924
Additions	2,626
Maturities/ terminations	(3,365)
Notional amount, end balance	2,185
Derivatives not designated as hedges | Equity Return Swaps
Derivative [Line Items]
Notional amount, beginning balance	326
Additions	17
Maturities/ terminations	(194)
Notional amount, end balance	149
Derivatives not designated as hedges | Other foreign currency contracts
Derivative [Line Items]
Notional amount, beginning balance	779
Additions	358
Maturities/ terminations	(1,069)
Notional amount, end balance	68
Derivatives not designated as hedges | Reinsurance embedded derivatives
Derivative [Line Items]
Notional amount, beginning balance	228
Additions	39
Maturities/ terminations
Notional amount, end balance	267
Derivatives not designated as hedges | GMWB embedded derivatives
Derivative [Line Items]
Notional amount, beginning balance	47,714
Additions	4
Maturities/ terminations	(1,323)
Notional amount, end balance	46,395
Derivatives not designated as hedges | Fixed index annuity embedded derivatives
Derivative [Line Items]
Notional amount, beginning balance	433
Additions	333
Maturities/ terminations	(6)
Notional amount, end balance	760
Derivatives Designated As Hedges
Derivative [Line Items]
Notional amount, beginning balance	14,571
Additions	117
Maturities/ terminations	(394)
Notional amount, end balance	14,294
Derivatives Designated As Hedges | Cash Flow Hedges
Derivative [Line Items]
Notional amount, beginning balance	13,447
Additions	117
Maturities/ terminations	(122)
Notional amount, end balance	13,442
Derivatives Designated As Hedges | Cash Flow Hedges | Interest rate swaps
Derivative [Line Items]
Notional amount, beginning balance	12,399
Additions
Maturities/ terminations	(122)
Notional amount, end balance	12,277
Derivatives Designated As Hedges | Cash Flow Hedges | Forward Bond Purchase Commitments
Derivative [Line Items]
Notional amount, beginning balance	504
Additions
Maturities/ terminations
Notional amount, end balance	504
Derivatives Designated As Hedges | Cash Flow Hedges | Inflation Indexed Swaps
Derivative [Line Items]
Notional amount, beginning balance	544
Additions	8
Maturities/ terminations
Notional amount, end balance	552
Derivatives Designated As Hedges | Cash Flow Hedges | Foreign currency swaps
Derivative [Line Items]
Notional amount, beginning balance
Additions	109
Maturities/ terminations
Notional amount, end balance	109
Derivatives Designated As Hedges | Fair value hedges
Derivative [Line Items]
Notional amount, beginning balance	1,124
Additions
Maturities/ terminations	(272)
Notional amount, end balance	852
Derivatives Designated As Hedges | Fair value hedges | Interest rate swaps
Derivative [Line Items]
Notional amount, beginning balance	1,039
Additions
Maturities/ terminations	(272)
Notional amount, end balance	767
Derivatives Designated As Hedges | Fair value hedges | Foreign currency swaps
Derivative [Line Items]
Notional amount, beginning balance	85
Additions
Maturities/ terminations
Notional amount, end balance	$ 85